1. Technical Field
The present invention relates to a lash adjuster.
2. Related Art
Japanese Patent Application Publication No. JP-A-2005-2953 discloses a lash adjuster which includes a bottomed cylinder (body) and a bottomed cylindrical plunger which is reciprocably inserted into the cylinder. A low-pressure chamber is defined in the plunger, and a high-pressure chamber is defined between the cylinder and a bottom wall of the plunger in the cylinder. The bottom wall of the plunger is formed with a valve orifice, and the high-pressure chamber houses parts composing a check valve mechanism, such as a valve portion which opens and closes the valve orifice, and the like.
An oil feed pipe is mounted on the plunger so as to extend through a peripheral wall thereof. The oil feed pipe is disposed to protrude obliquely upward into the low-pressure chamber. The oil feed pipe has an upper end reaching the vicinity of a top of the plunger. An operating oil from the cylinder head side is fed through the oil feed pipe into the low-pressure chamber thereby to be stored in the low-pressure chamber. When fluctuations in hydraulic pressure cause the valve portion to depart from the valve orifice of the bottom wall, the operating oil stored in the low-pressure chamber is fed through the valve orifice into the high-pressure chamber.
The above-described construction can render the lash adjuster smaller in size. Even when the low-pressure chamber cannot ensure a sufficient inner volume, the operating oil in the low-pressure chamber is stored up to a height position corresponding to the upper end of the oil feed pipe. This can prevent air in the low-pressure chamber from being suctioned into the high-pressure chamber due to shortage of operating oil in the low-pressure chamber. In particular, when the lash adjuster is inclined relative to the horizontal direction due to a mounting angle of engine, stop of a vehicle on a slope or the like, an amount of operating oil in the low-pressure chamber is reduced to a significant degree if no oil feed pipe or equivalent thereto is provided. Therefore, there is a great advantage in employment of the foregoing construction.
However, the oil feed pipe is added as an additional part of the lash adjuster in the above-described construction. This increases the number of parts and complicates the parts control. Additionally, a work of mounting the oil feed pipe to the peripheral wall has a possibility of causing works hardship.